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Study of energy and timing characteristics of 38.1mm?×?38.1mm CeBr3 scintillator detectors
摘要： We report the results of measurements and GEANT4 simulation for the performance of two 38.1mm × 38.1mm CeBr3 detectors. The linearity and energy resolution of both the detectors have been measured using low energy gamma sources in the range from 121.8 keV to 4.44 MeV. Maintaining the energy linearity condition, the best time resolution value of 423 ± 14 ps was measured for 1173–1332 keV photon pair from a 60Co source. A GEANT4 simulation was performed to reproduce the measured experimental spectrum and to estimate the absolute photopeak efficiencies at several energies up to 4.44 MeV.
关键词： Time resolution,GEANT4 simulation,Energy resolution,Scintillator,CeBr3
更新于2025-09-23 15:22:29
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Effects of temporary fogging and defogging in plastic scintillators
摘要： Recent studies have shown that under certain environmental conditions, plastic scintillators which are used in a variety of applications in outdoor environments develop defects called "fogging", resulting in a reduced useful lifetime and increased maintenance cost. Applications of plastic scintillators include scanning recycled steel going into a processing plant, personnel portals to scan employees, and scanning cargo and cars crossing borders of many countries. In this report, fogging was studied in conventional PVT and PS-based plastic scintillators, both field aged and freshly cast. A new fogging-resistant PVT-based formulation developed by scientists at Lawrence Livermore National Laboratory (LLNL) was tested as well. We used accelerated aging experiments via temperature and humidity cycling in controlled laboratory conditions to create observable temporary fogging defects in small samples (≤1 in3). Photoluminescence and optical transmission studies were used to evaluate the effect of the fogging. The time evolution of the induced temporary fogging formation and defogging (i.e. fading of defects in ambient conditions over time) were recorded using optical microscopy, time-lapse photography, and gravimetric analysis.
关键词： Accelerated aging,Optical microscopy,Scintillator,Gamma detection
更新于2025-09-23 15:22:29
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Prospective scintillation electron detectors for S(T)EM based on garnet film scintillators
摘要： The performance of a scintillation electron detector for a scanning electron microscope and/or a scanning transmission electron microscope (S(T)EM) based on new epitaxial garnet film scintillators was explored. The LuGAGG:Ce and LuGAGG:Ce,Mg film scintillators with chemical formula (Ce0.01Lu0.27Gd0.74)3–wMgw(Ga2.48Al2.46)O12 were prepared and their cathodoluminescence (CL) and optical properties were studied and compared with the properties of current standard bulk single crystal YAG:Ce and YAP:Ce scintillators. More specifically, CL decay characteristics, CL emission spectra, CL intensities, optical absorption coefficients, and the refractive indices of the mentioned scintillators were measured. Furthermore, electron interaction volumes with absorbed energy distributions, photomultiplier (PMT) photocathode matchings, modulation transfer functions (MTF), and the photon transport efficiencies of scintillation detectors with the mentioned scintillators were calculated. A CL decay time for the LuGAGG:Ce,Mg film scintillator as low as 28 ns with an afterglow of only 0.02% at 1 μs after the e-beam excitation was observed. As determined from calculated MTFs, the scintillation detectors with the new film scintillators lose contrast transfer ability above 0.6 lp/pixel, while the currently commonly used YAG:Ce single crystal scintillators already do so above 0.1 lp/pixel. It was also calculated that the new studied film scintillators have an 8% higher photon transfer efficiency, even for a simple disk shape compared with the standard bulk single crystal YAG:Ce scintillator. The studied LuGAGG:Ce,Mg epitaxial garnet film scintillators were evaluated as prospective fast scintillators for electron detectors, not only in S(T)EM but also in other e-beam devices.
关键词： electron detector,multicomponent garnet film,scintillator,STEM,SEM,LuGAGG:Ce,Mg,cathodoluminescence
更新于2025-09-23 15:22:29
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Temperature dependence of scintillation responses in rare-earth-ions-doped LiCaAlF6 single crystals
摘要： We have tested high-temperature responses of prototype neutron detectors equipping Ce-doped lithium silicate glass (GS20), LiCaAlF6:Ce, LiCaAlF6:Eu, LiCaAlF6:Ce, Na, and LiCaAlF6:Eu, Na. These detectors were prepared by coupling of the scintillators to a photomultiplier tube (PMT) for high-temperature environments (R1288, Hamamatsu). In the pulse height spectra under thermal neutron irradiation in the temperature range from 25°C to 150°C, peak heights of all the samples decreased with increasing temperatures. The decreasing rates for the peak heights of LiCaAlF6 scintillators were lower than that of GS20. The LiCaAlF6 scintillators can be used in the temperature range from 25°C to 150°C.
关键词： fluoride,scintillator,neutron,single crystal
更新于2025-09-23 15:21:01
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A mm <sup>3</sup> Fiber-Coupled Scintillator for In-Core Thermal Neutron Detection in CROCUS
摘要： The article presents the development, characterization and in-core testing of a miniature neutron detector for the investigation of highly localized in-core neutronics effects in the zero-power reactor CROCUS, operated at école Polytechnique fédérale de Lausanne (EPFL), Switzerland. A ZnS:6LiF screen, mixing inorganic scintillator and neutron converter, with a surface of 1 mm2 and a thickness of 0.2 mm was coupled with a silicon photomultiplier (SiPM) via a 10-m optical fiber. Analog read-out electronics were adopted in this prototype version to process the SiPM output signal. A first campaign was carried out to assess the detection system capabilities in terms of neutron detection and counting in mixed neutron-gamma radiation fields. The miniature detector was thoroughly characterized with a Pu-Be source installed in the CARROUSEL facility, and subsequently tested inside a control rod guide tube of the CROCUS reactor in different reactor conditions, i.e. at shutdown, startup and critical. The detector shows a linear response with the reactor power increase up to 6.5 W (i.e. around 108 cm-2·s-1 total neutron flux) and excellent neutron counting capabilities when compared to other localized detection systems available in CROCUS, such as miniature fission chambers and sCVD diamond detectors. In addition, the exposure of the miniature detector to a 60Co source with an activity of ～250 GBq, combined with the computation of the gamma flux in CROCUS with the Serpent 2 Monte Carlo code, confirmed the gamma insensitivity of the system in a mixed neutron-gamma field.
关键词： miniature neutron detector,CROCUS zero-power reactor,optical fiber devices,in-core neutron detectors,miniature scintillator devices
更新于2025-09-23 15:21:01
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Performance study of LaBr3:Ce detectors coupled to R2083 PM tube for energy and timing characteristics
摘要： Performance of 1″ × 1″ LaBr3 (5% Ce) scintillator coupled to Hamamatsu R2083 PM Tube has been investigated for the first time. Energy response and timing characteristics of the present assembly have been studied at different operating conditions for its application in fast timing spectroscopy. An energy resolution of 3.38 ± 0.03% at 662?keV γ-energy was obtained in the present work at a bias voltage of ? 2800?V and a linear response could be observed up to a bias voltage of ? 2500?V. Time resolution of a single LaBr3:Ce crystal was found to be 174 ± 2?ps and 121 ± 3?ps for 511–511 and 1173–1332 cascades respectively. Effect of applied bias voltage on the time resolution of the set up was studied and a steady improvement with increasing bias voltage was observed. Present results were compared with the previous results obtained with similar fast PM tubes and importance as well as implications of the present measurement were also discussed.
关键词： Linearity,R2083 PMT,Scintillator,LaBr3:Ce,Energy,γ-ray,Resolution,Hamamatsu
更新于2025-09-23 15:21:01
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Growth and characterization of Cs2LiLaCl6:Ce single crystals
摘要： Cs2LiLaCl6:Ce (CLLC) is a promising scintillator material for dual gamma/neutron detection. The vertical Bridgman technique, with a LiCl-rich melt and high axial temperature gradient, was used to grow transparent CLLC crystals for the first time. The stoichiometric CLLC powder melted incongruently with a melting range of 343-442 oC. Additional LiCl suppressed the formation of Cs3LaCl6 second phase, which was identified in crystals grown from stoichiometric melts. CLLC was found to have a Stokes shift of about 1358 cm-1 and a photoluminescence decay time of 34.6 ns. Direct electron-hole capture by Ce3+ ions and core-valence luminescence were the main contributors to the X-ray induced luminescence spectrum. A 9×8 mm3 cylinder of the CLLC crystal with 0.5at% Ce had an energy resolution of 7.1% at 662 keV. The scintillation decay times of the CLLC crystal excited with 662 keV gammas were 79 ns and 1491 ns.
关键词： A1. Absorption spectra,B2. Scintillator materials,B1. Cs2LiLaCl6:Ce,B3. Neutron detection,A2. Bridgman technique
更新于2025-09-23 15:21:01
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LiF based scintillation neutron detector at high counting rates
摘要： In this work we revisit the problem of the restricted count rate capability of thermal neutron detectors utilizing the ZnS scintillator. The effect of the long afterglow of the scintillator on the detector performance at high counting rates is studied. A count rate capability substantially above values currently regarded as feasible is demonstrated.
关键词： thermal neutron detector,SiPM,ZnS:6LiF scintillator,count rate capability
更新于2025-09-23 15:21:01
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Fiber-reading radiation monitoring system using an optical fiber and red-emitting scintillator for ultra-high dose condition
摘要： We have developed a remote scintillation detector using a CCD spectrometer and a red-emitting scintillator coupled with a 20-meters optical fiber for ultra-high-dose condition. Gamma-rays were detected with a conventional deep-red-emitting ruby scintillator and Cs2HfI6 which is a novel material with 700-nm red emission and a high light output. The scintillators were irradiated with gamma-rays from a 60Co source under the effective dose rate from ~0.002 to ~1 kSv/h. The integrated area of the Cs2HfI6 emission spectra was larger than that of the ruby, and the good linearity of Cs2HfI6 signal as a function of dose rate was confirmed.
关键词： radiation monitoring,optical fiber,ruby,ultra-high dose,Cs2HfI6,scintillator
更新于2025-09-23 15:19:57
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Prototype of an array SiPM-based scintillator Compton camera for radioactive materials detection
摘要： Purpose The Compton camera, which visualizes the distribution of gamma-ray sources based on the kinematics of Compton scattering, has advantage of wide field of view, broad range of energy and compact structure. Methods In this study, we proposed a prototype of Compton camera, which included array silicon photomultiplier (SiPM)-based position-sensitive detectors, data acquisition (DAQ) system and image reconstruction system. The detectors were composed of Ce-doped Gd3Al2Ga3O12 scintillator arrays and pixel Si-PM arrays. In DAQ system, symmetric charge division circuit, impedance bridge circuit and the delay coincidence algorithm were designed to record coincidence events. Simple back-projection algorithm and list-mode maximum likelihood expectation maximization algorithm were adopted for image reconstruction. The coordinate of longitude and latitude was used for image fusion. Results The performance of this Compton camera prototype system was evaluated. The results indicated that this system was able to locate a 137Cs point source within 20 s with the corresponding radiation dose of ~ 1.0 μSv/h. The angular resolution of point source was ~ 7° (FWHM), and the total energy resolution of 662 keV was 7.2%. Furthermore, we succeeded in separating two point sources of different energy [22Na (511 keV), 137Cs (662 keV)] in laboratory test. Conclusions This prototype of scintillator Compton camera offers capabilities for applications like source term investigation and radioactive materials detection.
关键词： Scintillator Compton camera,Image reconstruction,Compton imaging,Silicon photomultipliers
更新于2025-09-19 17:15:36